The Wave Dragon overtopping device elevates ocean waves to a reservoir above sea level where water is let out through a number of turbines and in this way transformed into electricity, i.e. a three-step energy conversion:
Overtopping (absorption) -> Storage (reservoir) -> power-take-off (low-head hydro turbines).
Power generation on the Wave Dragon is based on the potential energy in the water that has overtopped the ramp and is temporarily stored in the reservoir. This reservoir contains approximately 8,000 m3 water that has to be let out through the turbines in between two waves.
A special, small sized and low headed turbine has been developed to be used in the Wave Dragon. The photo shows this Kaplan turbine during the testing at the Technical University of Munich. This turbine uses a siphon inlet whereas the next 6 turbines to be installed will be equipped with a cylinder gate to start and stop water inlet to the turbine.
More information can be found on : http://www.wavedragon.net
Table 1: Wave Dragon production and expected cost in €/ kWh.
Table 2: Wave Dragon expected capital cost in €/ kW price.